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Comparison of cryothermal with radiofrequency catheter ablation for AV nodal reentrant tachycardia in a pediatric population
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Heart Rhythm, Vol 2, No 5, May Supplement 2005
P1-85 CRYOABLATION OF PARAHISSIAN PATHWAYS IN CHILDREN Arnold L. Fenrich, Jr., MD, Naomi J. Kertesz, MD, Richard A. Friedman, MD and Bryan C. Cannon, MD. Texas Children’s Hospital, Houston, TX. Introduction: Radiofrequency catheter ablation of paraHissian pathways raises concern for AV node injury. CryoAblation is advocated as a safe alternative for ablations near the AV node. Purpose: To assess the efficacy and incidence of AV node injury during CryoAblation of paraHissian pathways. Methods: We performed a retrospective review of all CryoAblations at our institution. Demographics, SVT mechanism, ablation data, complications and outcome were recorded. Results: A total of 37 patients underwent CryoAblation for SVT, of which 5 (see table) had a paraHissian pathway. The average age was 11.6 ⫾ 1.8 years. All demonstrated a His bundle electrogram at the site of successful ablation. All were acutely successful and no cases were terminated prematurely due to proximity to the AV node. Two of 5 had recurrence of preexcitation, but only one had recurrence of SVT. None are on antiarrhythmic medications. Mean follow-up was 8.3 ⫾ 6.5 months. Transient AV node injury occurred in 2 patients with complete recovery of AV node function immediately upon termination of Cryo. In patient #1, AV node injury was evidenced by maximal preexcitation at the onset of a CryoMapping (-30°C). In patient #4, loss of preexcitation and AV block occurred at the onset of a CryoAblation (-70°C). There was no permanent AV node injury. Permanent RBBB occurred in patient #4. Conclusions: CryoAblation provides an effective means for ablation of paraHissian pathways with the ability to ensure AV node conduction remains intact. The reassurance of maintenance of AV node conduction allows for perseverance in ablations near the AV node with the use of CryoAblation.
P1-86 COMPARISON OF CRYOTHERMAL WITH RADIOFREQUENCY CATHETER ABLATION FOR AV NODAL REENTRANT TACHYCARDIA IN A PEDIATRIC POPULATION Timothy K. Knilans, MD, Diane L. Proctor, RN, MSN, Paula Y. Koch, RN, BSN, Mary T. Rust, RN, BSN and Debbie J. Stamper, RN, BSN. Cincinnati Children’s Hospital Medical Center, Cincinnati, OH. Cryothermal catheter ablation (CT) has been proposed as a safer alternative to radiofrequency catheter ablation (RF) for arrhythmia substrates in proximity to the AV node. The safety and effectiveness of CT versus RF have not been reported in a pediatric population. Methods: Consecutive cases of CT for AV nodal reentrant tachycardia (AVNRT) were compared to an immediately previous series of RF performed by a single electrophysiologist in the same laboratory. The same anatomic based approach was used in all studies. Lack of inducibility of sustained AVNRT was considered acute success. Results: 45 consecutive patients underwent study and catheter ablation for AVNRT.
Of the 8 patients with acutely unsuccessful CT, 6 had RF during the same study with all being successful. No patient had significant damage to the fast AV nodal pathway or had any significant procedural complication. Conclusion: CT may offer a safer approach to catheter ablation of arrhythmia substrates in proximity to the AV node, but its acute effectiveness in this series was significantly worse than RF and there was a trend to higher likelihood of recurrence. This may represent a “learning curve” for CT and results may improve with application of different procedural strategies. P1-87 REPEAT LONG QT SYNDROME GENETIC TESTING OF PHENOTYPE POSITIVE CASES: PREVALENCE AND ETIOLOGY OF DETECTION MISSES Melissa L. Will, BSc, David J. Tester, BSc, Benjamin A. Salisbury, PhD, Janet L. Carr, Vincent Schulz, PhD, Richard S. Judson, PhD and *Michael J. Ackerman, MD, PhD. Mayo Clinic College of Medicine, Rochester, MN and Genaissance Pharmaceuticals, New Haven, CT. Background: Long QT syndrome (LQTS) genetic testing has been performed since 1995. Approximately 75% of patients with definite LQTS have an identifiable mutation in one of 5 LQTS-causing channel genes. Possible explanations for genotype negative cases include LQTS phenocopies, novel LQTS-causing genes, unexplored regions of the known genes, and genetic testing detection failures. Here, we sought to determine the prevalence and etiology of detection misses from our research laboratory. Methods: No LQTS-causing mutations were seen in 166/388 (43%) consecutive, unrelated patients who had been referred to Mayo Clinic’s Sudden Death Genomics Laboratory for LQTS genetic testing that utilized denaturing high performance liquid chromatography (DHPLC). Among this genotype negative subset, 46 subjects (29 female, average age ⫽ 23 ⫾ 15 years, average QTc ⫽ 512 ⫾ 55 ms) having the highest clinical likelihood for LQTS were selected for repeat genetic testing using direct DNA sequencing. Results: Putative LQTS-causing mutations were identified in 7/46 (15%) phenotype positive/previously genotype negative subjects including 4 with LQT1 (S225L, G568R, R591H, and R594Q), 2 with LQT2 (H70R and G925R), and 1 with LQT3 (V411M). None of these variants were seen in over 1500 reference alleles. Analysis of the misses revealed 1) normal DHPLC detection profile in 2 (detection method failure), 2) faulty DHPLC column in 1 (equipment failure), 3) allelic drop-out in 2 (primer design miss), and failure to detect abnormal signal in 2 (user miss). Conclusions: In this study, a LQTS-causing mutation was elucidated in 15% of subjects who had completed mutational analysis in our research laboratory and were deemed genotype negative. Extrapolation of this data suggests an approximate 95% accuracy with respect to our DHPLC-based genetic testing platform. Analysis of the “misses” revealed several different etiologies that have been addressed to improve detection of channelopathy-associated mutations. Repeat genetic testing should be considered for genotype negative individuals in whom the clinical diagnosis was strongly suspected. P1-88 LEAD PLACEMENT IN THE RIGHT VENTRICULAR OUTFLOW TRACT RESULTS IN 80% REDUCTION IN ODDS OF LEAD OUTGROWTH *Naomi J. Kertesz, MD, *Bryan C. Cannon, MD, James Comeaux, BS, *Michelene C. Minor, RN, BSN, E. O’brian Smith, PhD, *Arnold L. Fenrich, Jr., MD and *Richard A. Friedman, MD. Texas Children’s Hospital, Houston, TX and Baylor College of Medicine, Houston, TX.
Heart Rhythm, Vol 2, No 5, May Supplement 2005
P1-85 CRYOABLATION OF PARAHISSIAN PATHWAYS IN CHILDREN Arnold L. Fenrich, Jr., MD, Naomi J. Kertesz, MD, Richard A. Friedman, MD and Bryan C. Cannon, MD. Texas Children’s Hospital, Houston, TX. Introduction: Radiofrequency catheter ablation of paraHissian pathways raises concern for AV node injury. CryoAblation is advocated as a safe alternative for ablations near the AV node. Purpose: To assess the efficacy and incidence of AV node injury during CryoAblation of paraHissian pathways. Methods: We performed a retrospective review of all CryoAblations at our institution. Demographics, SVT mechanism, ablation data, complications and outcome were recorded. Results: A total of 37 patients underwent CryoAblation for SVT, of which 5 (see table) had a paraHissian pathway. The average age was 11.6 ⫾ 1.8 years. All demonstrated a His bundle electrogram at the site of successful ablation. All were acutely successful and no cases were terminated prematurely due to proximity to the AV node. Two of 5 had recurrence of preexcitation, but only one had recurrence of SVT. None are on antiarrhythmic medications. Mean follow-up was 8.3 ⫾ 6.5 months. Transient AV node injury occurred in 2 patients with complete recovery of AV node function immediately upon termination of Cryo. In patient #1, AV node injury was evidenced by maximal preexcitation at the onset of a CryoMapping (-30°C). In patient #4, loss of preexcitation and AV block occurred at the onset of a CryoAblation (-70°C). There was no permanent AV node injury. Permanent RBBB occurred in patient #4. Conclusions: CryoAblation provides an effective means for ablation of paraHissian pathways with the ability to ensure AV node conduction remains intact. The reassurance of maintenance of AV node conduction allows for perseverance in ablations near the AV node with the use of CryoAblation.
P1-86 COMPARISON OF CRYOTHERMAL WITH RADIOFREQUENCY CATHETER ABLATION FOR AV NODAL REENTRANT TACHYCARDIA IN A PEDIATRIC POPULATION Timothy K. Knilans, MD, Diane L. Proctor, RN, MSN, Paula Y. Koch, RN, BSN, Mary T. Rust, RN, BSN and Debbie J. Stamper, RN, BSN. Cincinnati Children’s Hospital Medical Center, Cincinnati, OH. Cryothermal catheter ablation (CT) has been proposed as a safer alternative to radiofrequency catheter ablation (RF) for arrhythmia substrates in proximity to the AV node. The safety and effectiveness of CT versus RF have not been reported in a pediatric population. Methods: Consecutive cases of CT for AV nodal reentrant tachycardia (AVNRT) were compared to an immediately previous series of RF performed by a single electrophysiologist in the same laboratory. The same anatomic based approach was used in all studies. Lack of inducibility of sustained AVNRT was considered acute success. Results: 45 consecutive patients underwent study and catheter ablation for AVNRT.
Of the 8 patients with acutely unsuccessful CT, 6 had RF during the same study with all being successful. No patient had significant damage to the fast AV nodal pathway or had any significant procedural complication. Conclusion: CT may offer a safer approach to catheter ablation of arrhythmia substrates in proximity to the AV node, but its acute effectiveness in this series was significantly worse than RF and there was a trend to higher likelihood of recurrence. This may represent a “learning curve” for CT and results may improve with application of different procedural strategies. P1-87 REPEAT LONG QT SYNDROME GENETIC TESTING OF PHENOTYPE POSITIVE CASES: PREVALENCE AND ETIOLOGY OF DETECTION MISSES Melissa L. Will, BSc, David J. Tester, BSc, Benjamin A. Salisbury, PhD, Janet L. Carr, Vincent Schulz, PhD, Richard S. Judson, PhD and *Michael J. Ackerman, MD, PhD. Mayo Clinic College of Medicine, Rochester, MN and Genaissance Pharmaceuticals, New Haven, CT. Background: Long QT syndrome (LQTS) genetic testing has been performed since 1995. Approximately 75% of patients with definite LQTS have an identifiable mutation in one of 5 LQTS-causing channel genes. Possible explanations for genotype negative cases include LQTS phenocopies, novel LQTS-causing genes, unexplored regions of the known genes, and genetic testing detection failures. Here, we sought to determine the prevalence and etiology of detection misses from our research laboratory. Methods: No LQTS-causing mutations were seen in 166/388 (43%) consecutive, unrelated patients who had been referred to Mayo Clinic’s Sudden Death Genomics Laboratory for LQTS genetic testing that utilized denaturing high performance liquid chromatography (DHPLC). Among this genotype negative subset, 46 subjects (29 female, average age ⫽ 23 ⫾ 15 years, average QTc ⫽ 512 ⫾ 55 ms) having the highest clinical likelihood for LQTS were selected for repeat genetic testing using direct DNA sequencing. Results: Putative LQTS-causing mutations were identified in 7/46 (15%) phenotype positive/previously genotype negative subjects including 4 with LQT1 (S225L, G568R, R591H, and R594Q), 2 with LQT2 (H70R and G925R), and 1 with LQT3 (V411M). None of these variants were seen in over 1500 reference alleles. Analysis of the misses revealed 1) normal DHPLC detection profile in 2 (detection method failure), 2) faulty DHPLC column in 1 (equipment failure), 3) allelic drop-out in 2 (primer design miss), and failure to detect abnormal signal in 2 (user miss). Conclusions: In this study, a LQTS-causing mutation was elucidated in 15% of subjects who had completed mutational analysis in our research laboratory and were deemed genotype negative. Extrapolation of this data suggests an approximate 95% accuracy with respect to our DHPLC-based genetic testing platform. Analysis of the “misses” revealed several different etiologies that have been addressed to improve detection of channelopathy-associated mutations. Repeat genetic testing should be considered for genotype negative individuals in whom the clinical diagnosis was strongly suspected. P1-88 LEAD PLACEMENT IN THE RIGHT VENTRICULAR OUTFLOW TRACT RESULTS IN 80% REDUCTION IN ODDS OF LEAD OUTGROWTH *Naomi J. Kertesz, MD, *Bryan C. Cannon, MD, James Comeaux, BS, *Michelene C. Minor, RN, BSN, E. O’brian Smith, PhD, *Arnold L. Fenrich, Jr., MD and *Richard A. Friedman, MD. Texas Children’s Hospital, Houston, TX and Baylor College of Medicine, Houston, TX.